How the brain sorts and routes messages

How do higher brain areas communicate with each other? Do they send out all computations equally to all target areas and leave the recipient to extract the needed and relevant information? Or does the transmitting region package and route computations differentially to distinct target areas, depending on the content? Ciocchi et al. found that the ventral hippocampus routes anxiety-related information preferentially to the prefrontal cortex and goal-related information preferentially to the nucleus accumbens. Hippocampal neurons with multiple projections were more involved in a variety of behavioral tasks and in memory consolidation.

Abstract

The hippocampus computes diverse information involving spatial memory, anxiety, or reward and directly projects to several brain areas. Are different computations transmitted to all downstream targets uniformly, or does the hippocampus selectively route information according to content and target region? By recording from ventral hippocampal CA1 neurons in rats during different behavioral tasks and determining axonal projections with optogenetics, we observed subsets of neurons changing firing at places of elevated anxiety or changing activity during goal approach. Anxiety-related firing was selectively increased in neurons projecting to the prefrontal cortex. Goal-directed firing was most prominent in neurons targeting the nucleus accumbens; and triple-projecting neurons, targeting the prefrontal cortex, amygdala, and nucleus accumbens, were most active during tasks and sharp wave/ripples. Thus, hippocampal neurons route distinct behavior-contingent information selectively to different target areas.